Rigid paperboard container

ABSTRACT

A paperboard container having an opening is wrapped in a shrinkwrapping, and the wrapping is shrunk over the container. The portion of the wrapping extending over the opening is displaced towards the innerside of the container and secured so as to leave the opening unobstructed. The wrapping of the container forms an integral part of the container.

United States Patent 1191 1111 3,834,607 Muylle Sept. 10, 1974 RIGID PAPERBOARD CONTAINER 3,072,517 11/132; gaylord 3.6 15??? 7 4 [75] Inventor: F' Edgal'd Schoten, 3/1965 229/Di0. 12 Belglum 3,337,114 8/1967 Lockwood 229/87 R 3,355,092 11/1967 Le Pain 229/87 R [73] Asslgnee' gfim' Mortsel 3,423,004 1/1969 Christensson... 229/14 BE 6 3mm 3,424,366 1/1969 Williamson 206/4533 ux 2 Filed; 23 1972 3,625,810 12/1971 Swartz 156/85 [21] Appl. No.: 248,408

Primary Exammer-W1ll1am I. Prlce Assistant Examiner-Stephen Marcus 1301 Forelgn Apphcauon Pnomy Data Attorney, Agent, or FirmWilliam J. Daniel Apr. 30, I971 Great Britain 12439/71 [52] US. Cl. 229/14 BA, 156/85, 206/4534, [57] ABSTRACT 229/14 BL, 229/23 BT, 229/37 R 51 Int. Cl B65d 5/56 PaPeKbmYd cmltamer havmg Penmg Wrapped 58 Field of Search 229/14 R, 14 BA, 14 BL, a ShImF'wraPPmg the is shrunk 229/14 Bw 14 BE 87 R DIG. 12 233 the contamer. The portlon of the wrapping extending 206/65 4533 4. 156/84 85 over the opening is displaced towards the innerside of 93/36 PC 54 f the container and secured so as to leave the opening unobstructed. The wrapping of the container forms an [56] References Cited integral part of the container.

UNITED STATES PATENTS 5/1962 Muskat et al. 53/30 5 Claims, 5 Drawing Figures PATENIEDsEH 0:914 834.607

SHEEI 1 or 2 Fig. 2

RIGID PAPERlBOARD CONTAINER The present invention relates to rigid or substantially rigid paperboard containers and to methods of manufacturing such containers.

In the photographic industry a package for sheets of light-sensitive material is known, which comprises one or more envelopes consisting of a lightand gasimpermeable material wherein the sheets or stacks of sheets are wrapped, and a rectangular paperboard box which comprises a base with a short shoulder inset and a telescope lid which cooperates with the shoulder inset of the base to afford extra rigidity to the box and to form a seal against admission of light to the box.

Conventional boxes are manufactured as follows. Flat sheets of boxboard are cut out and scored to size. These individual blanks are then separated from the sheet and the corners are cut out. Sides of the blanks are folded at right angles to the base to form the sides of a tray. Corners of the tray, for both the base and lid, may then be reinforced with paper, cloth or metal. Finally, a decorative paper covering or wrapping is adhered to the box, and a rectangular shoulder inset is glued to the base.

Whereas the cutting and folding of the boxboard blanks may be carried out almost entirely automatically, the application of the paper wrapping requires considerable manual labour. Besides, it has been shown that the resistance to abrasion of the paper wrapping may be insufficient so that boxes which are repeatedly used by clients, for instance for storage of developed film sheets or as a light-tight magazine for transport of exposed sheets to the room where the processing apparatus is located, may rapidly present an unsightly appearance. Wrapping papers which are coated with a protective lacquer or a plastic laminate ofier only a limited improvement against the deterioration of the neat appearance of the box in use.

The present invention aims at providing an improved container which is less subject to damaging than the known containers. In particular the invention aims at providing an improved method of manufacturing containers, which requires almost no manual intervention in the production process.

The method of manufacturing or covering a paperboard container, in particular a substantially rigid paper-board container which has at least oneopening is characterized by the step of wrapping the container in a shrink-wrapping and before, during or after shrinking such wrapping displacing the portion of the wrapping which extends over said at least one opening towards the innerside of the container and securing said displaced portion adjacent an inner face so as to leave the opening unobstructed.

Preferably, the portion of the wrapping which has been displaced towards the innerside of the container is secured in position e.g., by securing it to an inner face or faces of the container or by introducing an inset through said opening, the opening, in either case being unobstructed by the wrapping.

A rigid paperboard container with at least one opening according to the present invention has a covering formed by a shrink wrapping which extends into the container through the said at least one opening and which is preferably permanently secured to such container.

It will be understood that the container and the method of manufacturing or covering it according to the present invention differ essentially from the technique known in the packaging industry as shrinkwrapping. According to this technique, a heat shrinkable film is shrunk around one single article or a bundle of articles. Whatever the type and the use of the packaged article may be, the shrink-wrapping is just temporary, and serves to immobilize one or more items or to form an overwrap which may protect the neat appearance of a product, or which may assist in the display thereof. In all cases the shrink-wrapping must be removed before the wrapped product can be used.

Thus, whereas the shrink-wrapping of known packages forms no integral part of the package, the wrapping according to the invention does form an integral part thereof, and at any time the contents of the container remain accessible to the user without rupture of the wrapping.

The invention will be described hereinafter by way of example with reference to the accompanying drawings in which:

FIG. 1 is a rigid container according to the present invention,

FIG. 2 is the base of the container being provided with the shrink wrapping,

FIG. 3 illustrates a method for providing the wrapping around the base of the container,

FIG. 4 illustrates the displacement of a portion of the wrapping towards the innerside of the base,

FIG. 5 is a section of the lid on line 5 of FIG. 1.

The rigid paperboard container shown in FIG. I has the form of a set-up box with a base 10 and a lid 11 which, for the sake of clarity, have been drawn separated from each other. The lid is of the semi-telescope type and fits over a shoulder inset 12 on the base thereby offering double-wall strength. The inset 12 is a rectangularly folded paperboard element which is inserted through the opening of the base and which may reach to the bottom of the base. The topside of the inset is bevelled thereby to afford greater accessibility to a stack of sheets 13 in the container.

The base is made out of paperboard which has been cut out, folded and glued to form a deep box, and which thereafter has been provided with a shrinkwrapping in the form of a heat-shrinkable bag, the lower edge of which is indicated by the dash and dot line 14, and the upper edge of which is lying inside the base and is indicated by the dash and dot line 15.

The way in which the shrink-wrapping has been applied around the base is further illustrated in FIG. 2. The paperboard base is slid downwardly, the open side turned upwardly, into a bag formed from a heatshrinkable film. The height of the bag exceeds the height of the base so that by heat-shrinking, the upper portion 16 of the bag 18 shrinks over the rectangular opening of the base and thereby leaves an oval opening 17. In a next operation, the portion of the bag which extends over the base opening is widened by means of a heated die which softens the wrapping film and forces it through the base opening towards the innerside of the base. After this operation, the upper portion of the wrapping takes the shape of the interior of the base, and the upper edge of the wrapping has a form as indicated by the line 15 in FIG. 1. If the wrapping film, or the inner faces of the base, have heat-sealing properties, the portion of the wrapping which is displaced towards the innerside of the container may be directly sealed to the vertical walls of the base. As an alternative, the mentioned portion of the wrapping may also be attached to said walls by glueing.

The rectangular inset 12 which is thereupon introduced into the base may aid to keep the portion 16 of the wrapping applied against the inner faces of the vertical walls of the base.

As mentioned already hereinbefore, the wrapping is functional as well as decorative since it constitutes an integral part of the base. Therefore, it may be interesting to use wrapping film which is coloured instead of using a conventional transparent wrapping material. In the case of the described container for photographic material, the wrapping may e.g., be an orange-red coloured film.

Different types of shrink-films which may be used for the wrapping are: polyester, polyethylene, polypropylene, polyvinyl chloride, polystyrene, polyvinylidene chloride copolymer, etc.

The description of the contents of the package and the identification of the product and its manufacturer may be done in a conventional way by means of a selfadhesive label, or by means of a label which is heatsealed to the wrapping film.

The lid of the container may be provided with a covering which is a shrink-wrapping similar to that applied to the base, but it may also be provided with a conventional paper decorative covering.

In the case of a container for photographic material as herein described, the inset 12 and the inner faces of the paperboard lid 11 are preferably black, so that a light trap is formed as the container is closed.

According to the method described hereinbefore, the shrink-wrapping applied to the base was in the form of a bag. Said bag had been formed by cutting a given length from a seamless film tube, the cutting occurring preferably by means of heated knives so that in the same operation the bottom seal, indicated by the line 14 in FIG. 1, could be formed. It will be understood that said method of applying the wrapping is discontinuous and, therefore, may involve difficulties if the operation is to be carried out automatically.

Other methods for the continuous application of the wrapping are described hereinafter.

In the device according to FIG. 3, a shrink-wrapping film 20 is drawn from a roll 21 and pulled over appropriate folding members (not shown) to become applied around a paper board base 22 which may be introduced into the folded wrapping film by suitable feed means according to the direction of the arrow 23. The wrapped base passes through guide members 24, 25, 26 while a sealing member 27 seals the engaging longitudinal edges of the wrapping film. This sealing may occur while the film margins overlap, but the film margins may also be applied with their common face to each other to form a fin and in the same operation the sealing may cut the fin from the film so that no extending portion remains after sealing. The longitudinal seal is indicated by line 30. Transverse sealing bars 28 and 29 are normally spaced from each other to permit the passage of a base, but they may be approached towards each other in timed relation to transversely seal and cut the wrapping between successive bases. A wrapped base is indicated by numeral 31. It should be noted that the wrapping of the container is not at all tight so that the operation of the described device is not critical.

The wrapped bases may be received on a conveyor belt which transports them through a hot-air tunnel to shrink the film onto the base. Contrary to the base shown in FIG. 2, the base according to the present treatment has its opening closed by the wrapping as shown in FIG. 4. Therefore, the heated die 32 which displaces the portion of the wrapping tensioned over the opening of the base towards the innerside of the container, while the base is resting on a support 33, may be provided with a cutting tool at its lower face so that it may first penetrate through the wrapping and then soften it by contact with its heated faces. The die may comprise a band heater around its periphery and a covering of Teflon (Registered Trademark) or the like over said heaters. Such like construction permits a rapid heating and cooling of the wrapping material which is being applied to the inner faces of the base, whereas at the same time any adherence of the die to the wrapping film is avoided.

According to another embodiment, two webs of shrink wrapping may be used, the second being applied to the base from the side of the base which is opposite to the side where the wrapping 20 is applied. In such a case two longitudinal seams have to be formed which may be located centrally of the narrow sides of the container may alternatively be located at the edges of one large side of the base if one wrapping web is considerably larger than the other one.

The sealingof the wrapping after it has been applied around the base may be done according to different techniques. Thus it is possible to weld the longitudinal seal or seals ultrasonically and to effect the transverse seals by hot bars mounted on inline overhead orbital chains. According to another technique, bands of pressure-sensitive adhesives may be applied just before a shrink-film is shaped into a tube.

In the manufacture of a container as described hereinbefore, dog-ears may be formed at the lower edge of the small sides of the base as indicated by numeral 35 in FIG. 3. It will be understood that the dog-ears 35 in FIG. 3 do not represent the actual size thereof, since the wrapping has not yet been heat-shrunk. According to the kind of wrapping material and the temperaturetime conditions of the heat-shrinking, it may occur that said dog-ears do not fully disappear during the conventional heat-shrinking. Therefore, sets of air jets may be provided in the arrangement for shrinking the wrapping which permit to locally control the shrinking, thereby minimizing or avoiding the formation of dog-ears.

The description hereinbefore related to the manufacturing of the base of the paperboard box. It will be clear that the same operations may be carried out for the manufacturing of the lid of the box. In the case of the lid, there is no contribution from an inset member to amplify the adherence of the wrapping to the inner faces of the lid and to improve the appearance of the innerside of the lid which may be disturbed by the uncontrolled curvature of the edge of the wrapping in a way similar to the edge 15 shown in FIG. 1.

Therefore, according to a particular embodiment of the invention, the length of the wrapping tube which will cover the lid is taken so much greater than the height of the lid that it becomes possible to extend the wrapping unto the bottom of the lid after the heatshrinking. By glueing then a rectangular piece of paperboard to the bottom of the lid, the edge portion of the wrapping inside the container is completely screened from the eye. This embodiment is illustrated in FIG. 5, which represents a cross-section on line 5 of the lid 11 according to FIG. 1, and wherein the edge portion of a wrapping 36 is applied to the bottom of the lid and covered with a rectangular piece of paperboard 37. For the sake of clarity, the wrapping has been represented by a single line which is drawn separated from the lid.

A container according to the invention may have other shapes than the one shown. Such other shapes may be cubes or cylinders, but special shapes such as oval, heart or triangular can also be manufactured easily. The at least one opening of the container may extend over the full cross-section of the container but it may also be considerably smaller. In the case of a container which is to be filled with a granulate material, for instance, the opening may be circular with a surface smaller than one tenth of the surface of the wall wherein it is provided. A cylindrical inset in a hard plastic may then be introduced through the opening and displace thereby the wrapping through the opening to the innerside of the container. The closing may occur by a conventional plastic or metal snap-fit or screw-on cap which co-operates with the inset.

Finally, the operations of heat-shrinking the wrapping and of displacing the portion of the wrapping which extends over the opening towards the innerside of the container may also be reversed. This may be advantageous, for instance, in the case of providing the lid of a box with a shrink-wrapping since in that case the portion of the wrapping at the outerside of the lid will be more heated by the passage through a conventional hot-air tunnel than the portion of the wrapping at the innerside, so that a good tightening of the wrapping around the lid and yet a sufficient freedom of tensioning inside the lid to permit an easy displacement into the lid, onto the bottom thereof may be obtained.

We claim:

1. A rigid paperboard container with at least one opening and interior walls extending from the edges of said opening generally at an angle to the plane of said opening; a shrink-wrapping tightly fitting around said container and having an opening therein generally corresponding to the container opening, said wrapping having marginal portions extending inwardly through said container opening in contact with said interior walls; and a generally rigid retaining insert disposed within said container in contact with said inwardly extending marginal portions of said wrapping, said insert having peripheral surface portions in generally tightly fitting engagement with said container interior walls to clampingly secure therebetween the marginal portions of the wrapper contacted thereby.

2. A paperboard container according to claim 1 wherein said insert is a generally tubular sleeve fitting at least partially in telescoping relation with said container interior walls.

3. The container of claim 2 wherein said tubular sleeve insert projects exteriorly of said container through the opening thereof and including a container lid telescopingly fitting over the exterior portion of said insert to close said container.

4. A paperboard container according to claim 1 including a bottom wall disposed in spaced parallel relation to the plane of said container opening and wherein the wrapping marginal portions extend into the container at least to said bottom wall.

5. A paperboard container according to claim 4 wherein said insert is a false bottom member disposed in close proximity to said bottom wall with the peripheral edges thereof in contact with the marginal portions adjacent said bottom wall. 

1. A rigid paperboard container with at least one opening and interior walls extending from the edges of said opening generally at an angle to the plane of said opening; a shrink-wrapping tightly fitting around said container and having an opening therein generally corresponding to the container opening, said wrapping having marginal portions extending inwardly through said container opening in contact with said interior walls; and a generally rigid retaining insert disposed within said container in contact with said inwardly extending marginal portions of said wrapping, said insert having peripheral surface portions in generally tightly fitting engagement with said container interior walls to clampingly secure therebetween the marginal portions of the wrapper contacted thereby.
 2. A paperboard container according to claim 1 wherein said insert is a generally tubular sleeve fitting at least partially in telescoping relation with said container interior walls.
 3. The container of claim 2 wherein said tubular sleeve insert projects exteriorly of said container through the opening thereof and including a container lid telescopingly fitting over the exterior portion of said insert to close said container.
 4. A paperboard container according to claim 1 including a bottom wall disposed in spaced parallel relation to the plane of said container opening and wherein the wrapping marginal portions extend into the container at least to said bottom wall.
 5. A paperboard container according to claim 4 wherein said insert is a false bottom member disposed in close proximity to said bottom wall with the peripheral edges thereof in contact with the marginal portions adjacent said bottom wall. 